Stress-relaxation test

The stress-Relaxation test (relaxation test) is a method used in Material testing to test material properties at elevated temperatures. It is similar to the test used to determine Creep Resistance (fatigue Strength).

In a stress-relaxation test, a test piece (test bar) is stretched by a specific amount at a defined temperature. During the test, the deformation is kept constant and the progression of the tensile Force is recorded. This force continuously decreases as a result of material creep. The stress-relaxation strength (relaxation strength) is ultimately defined by the Residual stress measured after an exposure period that is also defined.

The data can be depicted graphically in a stress-time diagram. It is then possible to read off both the stress-relaxation resistance and the values for the relaxation (relief) rate and time.